What are the prayers that must be repeated after discovering traces of a wet dream after the 'Isha prayer, without certainty of whether it occurred before the Fajr or 'Asr prayer?

Only the 'Asr, Maghrib, and 'Isha prayers need to be re-offered, because the ritual impurity (hadath (definition)) is added to the end of their times. The original presumption is that the worshipper was in a state of purity at the time of the Fajr and Dhuhr prayers, and the occurrence of a wet dream at that time is doubtful. Certainty is not dispelled by doubt.